Centrifugal dust-separator



H- MILLIKEN. CENTRIFUGAL DUST SEPARATOR. APPLICATION FILED SEPT. 20, 1919.

Rammed Mar. 29 1921,

2 SHEETSSHEET 1.

amvamw H. MlLLiKEN. CENTRiFUGAL DUST SEPARATOR.

APPLICATION FILED SEPT. 20| 1919- Emmi Mar, 29, 1921.

2 SHEETS-SHEET,2.

EEUIEFHREYS BEILL'LKIEET, G NEW roan, I l. .21, ASSIGNOE 0F UNE-EALF EW J'QSE'EEI B.

TAYLOR, 03? NEW EDIE/1'21, Ill. I

Specification of Letters Eatent.

llatented Illa/r, 255), f

A; lication filed Eleptemcer '20, 1919. Serial No. 325 1%.

To (ZZZ whom; it may concern:

Various forms of apparatus have been hitherto constructed for this general purpose, the operation of which depends upon centrifugal action set up by causing the dust-laden ases to pass through mechanism to which a igh'rotary velocity is imparted. Apparatus of this character presents a variety of difficulties incident to practical construction and operation, among which may be mentioned the necessity of accurate hal- GAD ancing and specially constructed forms of mounting due to the high velocities used, as "well as the losses due to the inevitable clearance between the rotating and stationary. parts of the apparatus.

It is a further disadvantageof the types of centrifugal separators just mentioned that'they require a considerable outlay of energy to drive them, besides being subject to great frictional losses and wear and tear, particularly in view of the dust present in the air and gases to be treated.

It is the principal object of my present invention to provide a novel form of centrifugal dust separator having no moving parts whatever; thereby avoiding all the .di ficulties and disadvantages above referred to.

My improved apparatus may be broadly described. as comprising one or more passages for a moving current of dust laden air or gas, within which are located means for imparting a rotatory or whirling motion to the same. These passe es are provided withsuitable openings t rough which the dust is driven by the centrifugal force thus created, and they are surrounded by a chamher or chambers intended to receive the dust.

In the preferred embodiment of my invention, means are further provided whereby the original general movement of translation of the entering stream is gradually modified seas suitably to prepare the same for treatment Within the separating apparatus. i also prefer to provideineans at the outlet of my apparatus whereby the velocity energy of the gases at the outlet of the separating element is converted into pressure energy tending to assist the general movement of the gases through the system.

A preferred embodiment of my invention is illustrated in the accompanying drawings, wherein Figure 1 is a longitudinal sectional view of a multiple unit separator, Fig. 2 is an end elevation of the same looking from the left in Fig. 1, Fig. 3 is a view partly in longitudinal section and partly in elevation of a single element or unit, Fig. 4 is a transverse section taken on the line 4l-i in Fig. 3, and Fig. 5 is an end view of a single element as seen from the right in 3.

In Fig. 3 is shown a single separating element on a relatively large scale, the same being interrupted in the middle to indicate indefinite length, and the portion at the left beingshown partly in section and partly in elevation, the central core and the helical blade being omitted for the sake of clearness.

Each separating unit comprises a tubular envelop suitably perforated and a central core carrying one or more continuous helical blades extending outwardly to the interior surface of the tubular envelop. in my preferred apparatus the dust openings take the form of one or more continuous helical slits having preferably the same helical inclination as the interior helical blade or blades. I

The interior of the tubular envelop is'not truly cylindrical but consists of successive helical ridges between the slits, so arranged that the 'dust particles striking at any point of the interior surface. will slide toward a larger radius under the action of centrifugal force, and thus be guided toward one of the 100 helical openings. These openings should be as close together as practicable, so that the dust will have to travel a minimum distance to reach any opening. Advantage is thus taken of the rolling action or eddy currents 105 of the dust-laden gas to The preferred form. of separating unit is 1 10 which the dust-laden gases are forced to travel, thus imparting to them. a whirling motion.

Means are provided for uniting the spiral wires 10 to form a strong, unitary, selfsupporting structure, and for this purpose I prefer to employ exterior longitudinal. supporting plates 14, applied at proper intervals around the enve ip, four of these being shown in Fig. a. 'lnese plates are preferably electrically spot-welded along one edge to each of the wires crossing beneath it. In Fig. 4 the lowermost plate let is inclinethas shown, so as to divert the dust as it leaves the envelop toward the bottom of the casing which surroundsthe separating element 01' elements.

This casing is shown at 15 in Figs. 1 and 2 as used with my preferred. niultiple-unit machine. In the form shown, the upper part of the casing is rectangular in cross section, being closed at its two ends by plates or walls 16, 17, between which extend the parallel separating elements 10. The lower portion of the casing forms a hopper 18, into which settles the dustthrown from the elements 10, which dust r.-ay be removed at intervals from the bottom 19.

During operation of the apparatus, the gas pressure within the outer closed casing is virtually equal to that within the separating elements, so thatin the ideal form only dust will pass out through the openings 1.1 under centrifugal force. It the casing were open from end to end, the difference in pressures at the opposite ends of the separating elements would make itself felt in the casing. This would cause a slight flow of gases passing out of each separating element near the inlet and returning to each element near its exit, whereby a certain amount of dust would be carried back into the outgoing stream, thus reducing the efiiciency of the apparatus.

In order to prevent this, the surrounding dust chamber is divided transversely into compartments by the partitions 20. These partitions surroundthe separating elements 10 closely, and extend far enough down at their lower edges to enter the heap of dust collecting in the bottom of the casing, which forms a seal. When the dustbin is empty, the swinging flaps 2.0 will hang vertically "and prevent gases from passing. During instant.

The dust, as it leaves each opening in each element, will move in a nearly tangential direction, finally falling, to the bottomof the dust chamber. In order to prevent the stream of dust leaving one element from interfering with that leaving an adjoining element, I prefer to employ a. longitudinal dust-guiding plate 21, placed a short distance above and nearly parallel with one upper quadrant of each element, as shown in a Fig. 4. This plate not only shields the element beneath it from the stream of dust leaving the element above it, but the confined space below the plate 21 promotes the formation of a rapid dust stream to one side. It is desirable in practice to have a slight flow of gas from inside each element through the helical openings into the dust chamber at all points, in order to make sure that there is no flow of gas in the contrary direction. To accomplish this, I prefer to employ the auxiliary di'aft system shown in Fi e. 1 and 2.

lore a blower 22 is arranged to draw gases from. the main pipe 23, and to discharge the same near the bottom of the incoming gas passage 24. The main 23-is connected by branches 25 to the difi'erent dust spaces between the partitions 20, and the desired degree of draft may be adjusted for each partition by means of separate valves 26 in said branches. The essential point is that in each compartment of the dust chamber the pressure of gas should be slightlyless than that just inside of the separating elements, thus insuring a slight outward flow of gas. 1

In order to get the best results, it is de sirable that the incoming gases should assume the helical or rotating movement gradually, instead of permitting them to impinge suddenly upon the steeply pitched blades 13 while moving in 'a straight path. For this purpose I employ at the inlet end of each separatig-element a preparing section wherein means" are provided for imparting the gradually increasing rotary motion. to the incoming gases. The/form pref ferred forthis means is shown in Flgs. 3

and 5, as comprising one or more blades having a gradually decreasing pitch (in creasing steepness) from the entrance of the preparing section onward.

(Kiln and divided into a plurality of compartments, and means for transferring gas to the inlet ends of said. elements comprising" a blower a main pipe and branch pipes with valves connecting the main pipe separately with each of said compartments.

ll. Dust separating apparatus comprising a pluality of separating elements of the character set forth in claim 1 hereof, a closed dust chamber surrounding the same, and guide plates placed near the outer surfaces of said separating elements and adapted to prevent interference between outward dust streams from mutually adjacent elements.

ie'rat i i 12. In a centrifugal dust separator, a separating element comprising a tubular envelop having a suitable opening and a helical partition Within the same in combination with a preparing section'comprising a tube and two helical blades Within the same Whose pitch decreases gradually toward the separating elementone-o 'fsaicl blades being con tinuous and merging into the separating partition and the-other blade extending only part Wayinto the preparing section. 25

In testimony whereof I have hereto set my hand on this 13th daycit September, 1919. HUMPHREYS MILLIKEN. 

